Dean Smith

Dean Smith
University of Nevada, Las Vegas | UNLV · Nevada Extreme Conditions Laboratory

MPhys PhD

About

48
Publications
5,647
Reads
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277
Citations
Additional affiliations
December 2019 - November 2021
Argonne National Laboratory
Position
  • Assistant Physicist
May 2016 - June 2019
University of Nevada, Las Vegas
Position
  • Postdoctoral Scholar
Education
August 2013 - March 2016
University of Salford
Field of study
  • Physics
September 2012 - August 2013
University of Hull
Field of study
  • Physics
September 2008 - June 2012
University of Hull
Field of study
  • Physics with Nanotechnology

Publications

Publications (48)
Article
Full-text available
The application of pressure allows for systematic tuning of the charge density of a material "cleanly", i.e. without changes to the chemical composition via dopants, and exploratory high pressure experiments can inform the design of bulk syntheses of materials that benefit from their properties under compression. Here, we report the electronic and...
Article
Full-text available
We present a CO2 laser heating setup for synchrotron x-ray diffraction inside a diamond anvil cell, situated at HPCAT (Sector 16, Advanced Photon Source, Argonne National Lab, Illinois, USA), which is modular and portable between the HPCAT experiment hutches. The system allows direct laser heating of wide bandgap insulating materials to thousands o...
Article
Full-text available
The stability, structure and properties of carbonate minerals at lower mantle conditions has significant impact on our understanding of the global carbon cycle and the composition of the interior of the Earth. In recent years, there has been significant interest in the behavior of carbonates at lower mantle conditions, specifically in their carbon...
Article
Full-text available
We report experimental evidence for a crossover between a liquidlike state and a gaslike state in fluid methane (CH4). This crossover is observed in all of our experiments, up to a temperature of 397 K, 2.1 times the critical temperature of methane. The crossover has been characterized with both Raman spectroscopy and x-ray diffraction in a number...
Article
Full-text available
The chemical reaction between hydrogen and purely sp2-bonded graphene to form graphene’s purely sp3-bonded analogue, graphane, potentially allows the synthesis of a much wider variety of novel two-dimensional materials by opening a pathway to the application of conventional chemistry methods in graphene. Graphene is currently hydrogenated by exposu...
Article
We present a portable CO 2 laser heating system for in situ x-ray absorption spectroscopy (XAS) studies at 16-BM-D (High Pressure Collaborative Access Team, Advanced Photon Source, Argonne National Laboratory). Back scattering optical measurements are made possible by the implementation of a Ge beamsplitter. Optical pyrometry is conducted in the ne...
Preprint
Full-text available
Dehydrogenation of alkanes is of increasing importance in fulfilling global demand for olefins and offers a potential source of carbon-neutral hydrogen as a co-product. Currently commercial dehydrogenation processes occur at high-temperatures (500-900$^\circ$C) which is energy intensive and results in side reactions and rapid coking of the catalyst...
Article
We report a previously unobserved superconducting state of the photosynthesized carbonaceous sulfur hydride (C-S-H) system with a maximum TC of 191(1) K below 100 GPa. The properties of C-S-H are dependent on carbon content, and X-ray diffraction and simulations reveal the system remains molecular-like up to 100 GPa.
Article
Full-text available
We present an experimental and theoretical study of dysprosium metal compressed in the soft pressure transmitting medium Ne up to 182 and 300 GPa, respectively. Angle-dispersive x-ray powder diffraction data from each of the high-pressure polymorphs shows anisotropic compression behavior indicating changes to the electron density distribution throu...
Preprint
Full-text available
The uniaxial compression design of the diamond anvil high pressure cell (DAC) necessitates the use of a soft pressure-transmitting medium (PTM) to minimize non-hydrostatic effects at significantly high pressures, and many such media are gaseous at ambient conditions. There now exist a number of commercially-available instruments - high-pressure gas...
Article
Full-text available
X-ray diffraction and Raman spectroscopy of H 2 O (ice) structures are measured under static compression in combination with grain normalizing heat treatment via direct laser heating. We report the transition from cubic ice-VII to a structure of tetragonal symmetry, ice-VII t at 5.1 ± 0.5 GPa. This is succeeded by the H-bond symmetrization transiti...
Article
Full-text available
Mg 2 GeO 4 is important as an analog for the ultrahigh-pressure behavior of Mg 2 SiO 4 , a major component of planetary interiors. In this study, we have investigated magnesium germanate to 275 GPa and over 2,000 K using a laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction and density functional theory (DFT) computa...
Preprint
Full-text available
Room-temperature superconductivity was recently discovered in carbonaceous sulfur hydride (C-S-H) close to 3\,Mbar. We report significant differences in the superconducting response of C-S-H, with a maximum $T_{C}$ of 191(1)\,K, below a 1\,Mbar. Variations in intensity of the C-H Raman modes reveal carbon content can vary between crystals synthesiz...
Article
Transition metal carbides find use in a wide range of advanced high-resilience applications including high-strength steels, heat shields, and deep-earth drills. However, carbides of the mid-to-late transition metals remain difficult to isolate and characterize on account of their metastability, which precludes the preparation of high-quality bulk s...
Article
We demonstrate the synthesis and phase stability of TcN, Tc2N, and a substoichiometric TcNx from 0–50 GPa and to 2500 K in a laser-heated diamond anvil cell. At least potential...
Article
Full-text available
A reversible density driven insulator to metal to insulator transition in high-spin MnS_2 is experimentally observed, leading with a colossal electrical resistance drop of 10^8 Ω by 12 GPa. Density functional theory simulations reveal the metallization to be unexpectedly driven by previously unoccupied S_2^(−2) σ^∗_(3p) antibonding states crossin...
Article
We report the synthesis and structure of the second allotrope of technetium, β−Tc. Transformative pathways are accessed at extreme conditions using the laser-heated diamond anvil cell and confirmed with in situ synchrotron x-ray diffraction and Raman spectroscopy. β−Tc is fully recoverable to ambient conditions, although counter to our DFT calculat...
Preprint
The $A$MnO$_{2}$ delafossites ($A$=Na, Cu), are model frustrated antiferromagnets, with triangular layers of Mn$^{3+}$~spins. At low temperatures ($T_{N}$=65 K), a $C2/m \rightarrow P\overline{1}$ transition is found in CuMnO$_2$, which breaks frustration and establishes magnetic order. In contrast to this clean transition, $A$=Na only shows short-...
Article
The AMnO2 delafossites (A = Na, Cu) are model frustrated antiferromagnets, with triangular layers of Mn3+ spins. At low temperatures (TN = 65 K), a C2/m → P1̅ transition is found in CuMnO2, which breaks frustration and establishes magnetic order. In contrast to this clean transition, A = Na only shows short-range distortions at TN. Here, we report...
Article
Water (H2O), in all forms, is an important constituent in planetary bodies, controlling habitability and influencing geological activity. Under conditions found in the interior of many planets, as the pressure increases, the H-bonds in water gradually weaken and are replaced by ionic bonds. Recent experimental measurements of the water equation of...
Article
Full-text available
Alkaline earth metal peroxides are typical examples of ionic compounds containing polyanions. We herein report a stable BaO2 phase at high pressure up to 130 GPa found via a first-principles computational structure search and high-pressure experimental investigations. The identified monoclinic structure (space group C2/m) can be derived by sublatti...
Preprint
Water (H$_{2}$O), in all forms, is an important constituent in planetary bodies, controlling habitability and influencing geological activity. Under conditions found in the interior of many planets, as the pressure increases, the H-bonds in water gradually weaken and are replaced by ionic bonds. Recent experimental measurements of the water equatio...
Article
The (NH4)2[ReF6] (1) salt was studied by X-ray diffraction, Raman spectroscopy, theoretical calculations, and magnetic measurements. 1 crystallizes in the trigonal space group Pm1 (Re–F = 1.958(5) Å). In the Raman spectrum of 1, splitting of the observed peaks was observed and correlated to the valence frequencies of vibration of the [ReF6]²⁻ anion...
Preprint
Full-text available
High-pressure phases of Mg$_2$GeO$_4$ have been explored as an analogue system for the ultra-high pressure behavior of Mg$_2$SiO$_4$. Using a laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction, we have identified a novel phase in which germanium adopts eight-fold coordination with oxygen. The cubic Th3P4-type phase...
Article
The lattice dynamic response of body-centered tetragonal β−Sn (I41/amd) under high-pressure and -temperature conditions is determined using experimental optical vibration modes. Raman scattering is used to map the phase stability region of β−Sn to perform mode Grüneisen analysis, and we demonstrate the necessity of an optical intensity calibration...
Article
With the exception of lithium, alkali metals do not react with elemental nitrogen either at ambient conditions or at elevated temperatures, requiring the search for alternative synthetic routes to their nitrogen-containing compounds. Here using a controlled decomposition of sodium azide (NaN3) at high pressure conditions, we synthesize two novel co...
Article
Full-text available
The transparent conducting oxide, SnO 2 , is a promising optoelectronic material with predicted tailorable properties via pressure-mediated band gap opening. While such electronic properties are typically modeled assuming perfect crystallinity, disordering of the O sublattice under pressure is qualitatively known. Here a quantitative approach is th...
Article
The effect of pressure on the room temperature solubility of hydrogen in Zircaloy-4 was examined using synchrotron X-ray diffraction on small ground flake samples in a diamond anvil cell at pressures up to 20.9 GPa. Different combinations of hydrogen level/state in the sample and of pressure transmitting medium were examined; in all three experimen...
Preprint
Full-text available
H2O is an important constituent in planetary bodies, controlling habitability and, in geologically-active bodies, plate tectonics. At pressures within the interior of many planets, the H-bonds in H2O collapse into stronger, ionic bonds. Here we present agreement between X-ray diffraction and Raman spectroscopy for the transition from ice-VII to ice...
Article
Full-text available
The employment of high-pressure gases as a pressure-transmitting medium, sample, or reactant for diamond anvil cell experiments is widespread. As a pressure transmitter, high-pressure gases are crucial to forming quasi-hydrostatic compression atmospheres for samples inside the uniaxially driven cell. We describe an optical design for forming high-r...
Article
The pyrite mineral MnS2 was recently shown to undergo a giant pressure-induced volume collapse at ∼ 12 GPa, via a disordered intermediate phase. The high pressure arsenopyrite phase is stabilised by metal-metal bonding, a mechanism now shown to be ubiquitous for Mn²⁺ chalcogenides. Here we report a spectroscopic investigation of this transition up...
Article
Full-text available
The application of pressure allows for systematic tuning of the charge density of a material "cleanly", i.e. without changes to the chemical composition via dopants, and exploratory high pressure experiments can inform the design of bulk syntheses of materials that benefit from their properties under compression. Here, we report the electronic and...
Preprint
Full-text available
The effect of pressure on the room temperature solubility of hydrogen in Zircaloy-4 was examined using synchrotron X-ray diffraction on small ground flake samples in a diamond anvil cell at pressures up to 20.9 GPa. Different combinations of hydrogen level/state in the sample and of pressure transmitting medium were examined; in all three cases exa...
Article
Full-text available
The A2[ReF6 ] (A = K, Rb and Cs) salts are isotypic and crystallize in the trigonal space group type P3m1, adopting the K2[GeF6] structure type. Common to all A2[ReF6] structures are slightly distorted octahedral [ReF6]2- anions with an average ReF bond length of 1.951 (8) A ˚. In those salts, symmetry lowering on the local [ReF6]2- anions from Oh...
Article
Full-text available
The A2[ReF6] (A = K, Rb and Cs) salts are isotypic and crystallize in the trigonal space group type Pm1, adopting the K2[GeF6] structure type. Common to all A2[ReF6] structures are slightly distorted octa­hedral [ReF6]²⁻ anions with an average Re—F bond length of 1.951 (8) Å. In those salts, symmetry lowering on the local [ReF6]²⁻ anions from Oh (f...
Article
The stability, structure and properties of carbonate minerals at lower mantle conditions has significant impact on our understanding of the global carbon cycle and the composition of the interior of the Earth. In recent years, there has been significant interest in the behavior of carbonates at lower mantle conditions, specifically in their carbon...
Article
We have studied the compressibility and stability of different β-titanium alloys at high pressure, including binary Ti-Mo, Ti-24Nb-4Zr-8Sn (Ti2448) and Ti-36Nb-2Ta-0.3O (gum metal). We observed stability of the β phase in these alloys to 40 GPa, well into the ω phase region in the P-T diagram of pure titanium. Gum metal was pressurised above 70 GPa...
Article
Full-text available
We study the structure of binary monolayers of large (3 μm diameter) very hydrophobic (A) and large (3 μm diameter) hydrophilic (B) or small (1 μm diameter) hydrophilic (C) silica particles at an octane-water interface. By tuning the composition and packing geometry of the mixed monolayer, we find that a rich variety of two-dimensional hexagonal su...

Questions

Question (1)
Question
I've seen the citation used quite widely in papers and presentations on hydrogen storage, but the PDF is unfortunately no longer available on NASA's online repository.
  • R.L. Smith, J.W. Miser
Compilation of the Properties of Lithium Hydride
NASA-TM-X-483, Glenn Research Center (1963)

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